Scalp

Question 1

The scalp gets sensory innervation from which nerve?

Answer 1

Trigeminal

Question 2

Which zone of the scalp is the danger zone for infection and why?

Answer 2

Loose connective tissue.
The loose connective tissue allows infection to enter the skull through the sutures via its venous drainage. It carries emissary veins (the veins connecting the scalp to the diploic veins and intercranial venous sinuses.

Question 3

What are the layers of the scalp?

Answer 3

S- skin
C- dense connective tissue 
A- aponeurosis
L- loose connective tissue
P- periosteum

Question 4

What is a cephalohaematoma and who gets them?

Answer 4

A subperiosteal haematoma
Newborns can develop a traumatic sepahlohaematoma in childbirth- note this is generally harmless and is not dangerous to underlying brain tissue

Question 5

Why are cephalohaematomas not dangerous to brain tissue?

Answer 5

The bleed is in the periosteum and this limits the spread of blood across suture lines.

Question 6

Why might a scalp wound gape?

Answer 6

If the aponeurosis has been severed then the pull of the two muscle bellies will pull the edges apart.

Question 7

Why does a bleed in the dense connective tissue give a bump on the head that is nice and circular?

Answer 7

DCT is very vascular and so bleeds a lot. The dense connective tissue is tightly adherent to the skin and underlying aponeurosis and contains lots of fibrous septa which limit the spread of blood through that plane.

Question 8

Why do scalps bleed a lot?

Answer 8

Dense connective tissue is very vascular and contains fibrous septa that adhere it to the aponeurosis. This will hold the vessels slightly open and prevent complete constriction after injury.

Question 9

The veins in the dense connective tissue join the inter cranial veinous drainage in what layer?

Answer 9

The loose connective tissue

Question 10

Which layer of the scalp could allow blood to track forward and allow presentation of a patient with black eyes that indicate a head injury?

Answer 10

The loose connective tissue has adherence of occiptofrontalis at the back which stops blood moving back. At the front however the insertion of frontlis is not into the bone and thus doesn’t limit blood flow forward and may lead to blood entering the orbit. This blood is more likely to be venous than arterial.